The invention relates to a retaining means for retaining an excavating tooth on a support while permitting replacement of the tooth when it is worn.
Large power shovels of the type commonly used to scoop iron ore or taconite from the ground following the blasting operation have a row of large teeth along the forward edge, or lip, of the floor of the shovel. These teeth are subject to extreme wear and are replaceable. A large shovel may have six such teeth, each tooth being shaped somewhat like a chisel point, 18 inches in length, 8.times.8 inches at the base, and weighing perhaps 120 lbs. The teeth are cast from one of several types of high strength, abrasion-resistant steel. Such shovels are used in all types of mining.
The shovel teeth are removably fastened to the lip of the shovel by means of various keeper pin systems. Each tooth incorporates a cavity in its base which mates with a projection on the lip of the shovel. In most cases, this projection is part of an intermediate piece called the "base" or "adapter", which in turn is removably fastened to the lip of the shovel.
When the tooth is placed on the base, the keeper pin is driven down through holes which are aligned in the tooth and base. The keeper pin thus is used to lock the tooth to the base. When the tooth is worn out, the keeper pin is removed, and a new tooth and keeper pin are assembled on the base.
There are a large number of different keeper pin systems in use in industry, and/or shown in prior art patents. For example: Philbrick U.S. Pat. No. 2,242,793; Larsen U.S. Pat. No. 2,709,941; Petersen U.S. Pat. No. 2,968,880; Stephenson U.S. Pat. No. 2,994,141; Eyolfson U.S. Pat. No. 3,121,289; Hofstetter U.S. Pat. No. 3,256,622; Phillips U.S. Pat. No. 3,334,431; Judkins et al U.S. Pat. No. 3,368,293; Duplessis U.S. Pat. No. 3,388,488; Hensley U.S. Pat. No. 3,444,633; Hensley et al U.S. Pat. No. 3,520,224; VonMehren U.S. Pat. No. 3,832,077; Hemphill U.S. Pat. No. 4,037,337 and Hahn et al U.S. Pat. No. 4,061,432. Unfortunately, none of the known keeper pin systems meet all the criteria of an "ideal" system which should: be simple and foolproof to install; rigidly secure the tooth to the base; not release in severe use; be simply released by one man; be installed and released by operating on the top of the tooth only; not be affected by weather extremes; and be inexpensive to manufacture.